Remote Sensing of Sea Ice at Small Incidence Angles: Verification of Theoretical Models

Sea ice is a complex structure and theoretical models have been developed to describe the scattering of electromagnetic waves. The area of small incidence angles remains the least studied both theoretically and experimentally. With the launch of a Dual-frequency Precipitation Radar (DPR) into orbit as part of the GPM mission, it became possible for the first time to analyze the dependence of the backscattered radar cross section (RCS) on the incidence angle for small angles (<20 degrees). The Okhotsk Sea was chosen as a test site. For three well-known scattering models, the performed comparison showed that, at the small incidence angles, the model constructed within the framework of the perturbation method best describes the dependence of the RCS on the incidence angle. However, synchronous measurements in the Ku- and Ka-bands showed that there is an unexplained change in the RCS in the framework of this theoretical model when passing from one frequency range to another. Research will continue to explain this effect and to improve the scattering model.